Method for generating a trigger signal for triggering at least one safety function of a motor vehicle

ABSTRACT

A method for generating a trigger signal for triggering at least one safety function of a motor vehicle. The method includes at least the following method steps: a) receiving respective signals from at least two pressure tube sensors, b) determining at least one collision parameter from the signals received according to step a), c) outputting the trigger signal for the at least one safety function as a function of the at least one collision parameter determined in step b).

BACKGROUND INFORMATION

Pressure tube sensors (PTSs) have been used for a number of years fordetecting a pedestrian collision on a front side of a motor vehicle. Thepressure tube is generally situated between a bumper crossbeam andabsorption foam situated in front of same. The pressure tube is filledwith air, and is closed off with a pressure sensor at each end. Thedeformation of the foam that occurs during a pedestrian collision thusresults in compression of the tube, as the result of which a pressuresignal is measured by the two pressure sensors. This pressure signal isread in by a control unit, generally the central airbag control unit,where it is processed in order to detect a pedestrian collision.

Vehicle accidents are conventionally recognized by an airbag controlunit, mounted on the vehicle tunnel, by use of an acceleration sensorsystem, optionally supplemented by an external sensor system.

SUMMARY

A particularly advantageous example method for generating a triggersignal for triggering at least one safety function of a motor vehicle inaccordance with the present invention is presented herein. Advantageousrefinements of the example method in accordance with the presentinvention are described herein.

The example method is based in particular on the finding that a pressuretube may be used not only for pedestrian recognition, but also forimproved recognition of vehicle accidents. This applies in particular toparticular types of vehicle collisions such as a pole impact in themid-region of the vehicle. Since no crash structures of the vehicle areaffected in a pole impact, it may be detected only relatively late witha conventional collision sensor system, whereas it may be recognizedvery quickly by the pressure tube. In addition, by use of the describedmethod the pedestrian protection recognition may be enhanced and mademore robust.

At least two pressure tube sensors are provided for the describedmethod. Based on these sensors, in particular important features ofcollisions, such as a collision speed (which may also be referred to asan intrusion speed) and/or a direction of the collision, may beidentified and used for improved collision recognition and triggering ofsafety functions (such as restraint means).

Thus, by use of the described method it is possible in particular tocontrol restraint means in a more precise and robust manner. This maytake place in particular in that the parameters of collision speed anddirection of impact, which are vitally important for the severity of thecollision, may be explicitly determined. This is not possible with aconventional sensor system. Instead, present collision algorithmsoperate with implicit features that allow only indirect conclusions tobe drawn concerning these key parameters. This results in relativelyinaccurate recognition of the type and severity of the collision.

A system that includes two pressure tube sensors (thus, a 2-PTS system)is preferably used for the described method. The pressure tube sensorsare preferably situated apart from one another. A system that includestwo pressure tube sensors is in particular a system with twowell-defined contact switches (the pressure tube sensors). The pressuretube sensors are preferably situated in a (in particular front) crumplezone of the motor vehicle. Key parameters for the severity of thecollision, in particular the collision speed and/or the direction ofimpact, may thus be determined. Explicitly determining the collisionspeed and/or the direction of impact may allow significantly moreprecise and accurate collision recognition, and thus, control of therestraint means required for the ascertained severity of the collision.

The described method includes in particular method steps a) through c),which are preferably carried out in the stated order.

Signals are received from each of at least two pressure tube sensors instep a) of the described method.

The pressure tube sensors preferably each include an air-filled tube(preferably made of a material containing silicone) that is closed offwith a pressure sensor at one end, preferably at both ends. In thefollowing discussion, as an example it is assumed that two pressuresensors are provided for each pressure tube sensor. Data may be recordedwith the pressure sensors, from which an impact on the tube may bededuced. Based on these data, in particular a signal of the pressuretube sensor may be generated via an appropriate electronics system. Thesignal may in particular indicate the fact that an impact has beendetected with the pressure tube sensor. The point in time that thesignal is output may indicate the point in time of the impact (possiblydelayed by a processing time). Alternatively, the signal may also becontinuously output and changed in a predefined manner when an impact isdetected.

The signals of the at least two pressure tube sensors are preferablyreceived by a control unit that is intended and configured for carryingout the described method.

At least one collision parameter is determined from signals receivedaccording to step a), in step b) of the described method.

Any variable that may characterize an accident of a motor vehicle issuitable as a collision parameter. The collision parameter is preferablydefined in such a way that it allows a conclusion to be drawn concerningthe type and/or severity of an accident. The collision parameter may inparticular be determined in the control unit, using appropriatesoftware.

A trigger signal for the at least one safety function is output in stepc) of the described method as a function of the at least one collisionparameter determined in step b).

The at least one safety function may be, for example, an airbag, a seatbelt tensioner, or an intervention into the control system of the motorvehicle (for example, via automatic emergency braking and/or anautomatically initiated evasive maneuver). The motor vehicle preferablyincludes a plurality of safety functions. The at least one safetyfunction may be triggered in particular by a trigger signal that ispreferably output in particular by the control unit. The type and/orseverity of the accident that is recognizable from the collisionparameter may be taken into account in step c) of the described methodin the triggering of the at least one safety function. Thus, the pointin time and/or the type of triggering of the at least one safetyfunction may be determined as a function of the collision parameter. Inaddition, it may be determined whether the at least one safety functionis to be triggered at all. In addition, for multiple safety functions aselection of safety functions to be triggered may be made, and/or adecision may be made regarding the particular order in which they are tobe triggered.

In one preferred specific embodiment of the example method, respectivesignals are received in step a) from at least two pressure tube sensorsthat are spaced apart from one another at least in the travel directionof the motor vehicle.

In the present context, the travel direction is understood to mean thedirection in which the motor vehicle is moving during typical forwardtravel. A frontal impact may be detected initially by the pressure tubesensor situated farther to the front in the travel direction, and onlyafter a delay, also detected by the other pressure tube sensor. Inparticular a collision speed may be determined by the time differencewith which the two pressure tube sensors detect the impact.

The pressure tube sensors may likewise be spaced apart from one anotherin a vertical direction, in particular transverse (or perpendicular) tothe travel direction. However, it is also possible for the pressure tubesensors to be situated at the same height in the vertical direction.

In another preferred specific embodiment of the example method, thesignals of the at least two pressure tube sensors received in step a) ineach case represent at least one of the following parameters:

-   -   an impact time t₁, t₂ and    -   an impact location s₁, s₂.

The statement that the received signals represent mentioned parametersof impact time (t₁, t₂) and impact location (s₁, s₂) means theinformation contained in the received signals, from which the mentionedparameters are ascertainable. Pressure patterns regarding the signalsreceived from the pressure tube sensors are preferably received in stepa). Based on these pressure patterns, it is then possible to compute animpact time (t₁, t₂) and an impact location (s₁, s₂) in a control unit(preferably the control unit in which the further method steps are alsocarried out).

In the event of an impact with an obstacle, initially the first pressuretube (at point in time t₁), and subsequently the second pressure tube(at point in time t₂), are deformed in succession. Both deformationsresult in an immediate pressure rise, and thus a pressure signal to thepressure sensors that close off the particular pressure tubes. Theparticular points in time t₁ and t₂ may be detected in the control unit,for example via threshold value exceedances of a first pressure sensorof the respective pressure tube sensor.

Impact time t₁ or t₂ is understood to mean the point in time at which animpact is detected with the first or second pressure tube sensor. Impactlocation s₁ or s₂ is the location at which the impact has been detectedwith the first or second pressure tube sensor. s₁ and s₂ are preferablydefined along the respective pressure tube sensors. Thus, for example,s₁ and s₂ may indicate the distance between the location of the impactand a midpoint of the pressure tube.

In another preferred specific embodiment of the method, the at least onecollision parameter determined in step b) is at least one of thefollowing parameters:

-   -   a magnitude of a collision speed v _(intr),    -   a component of collision speed v_(intr,x) along the travel        direction of the motor vehicle,    -   a collision angle α.

Collision speed v_(intr) is a vectorial variable that includes at leastone component along travel direction x of the motor vehicle, v_(intr,x),and a component perpendicular thereto, v_(intr,y). v _(intr), is themagnitude of vector v_(intr). Collision angle α is the angle at which acollision object strikes the motor vehicle, i.e., its front side.

Based on time difference Δt=t₂−t₁ between points in time t₂ (pressurerise in the second pressure tube) and t₁ (pressure rise in the firstpressure tube), and longitudinal distance d in the travel directionbetween the two pressure tube sensors, (averaged) collision speed v_(intr,x) may be directly ascertained from

v _(intr,x) =d/Δt.   (1)

For the case that both pressure tube sensors are mounted a largedistance apart in the motor vehicle (in particular in front of fairlyhard crash structures such as crash boxes), in a good approximation itmay be assumed that in the early collision phase, in which the twopressure tube sensors are deformed, an appreciable decrease in speed hasnot yet taken place due to the collision. This applies even more, thehigher the collision speed. This means that the two collision partnersare still moving virtually at the initial speed. This means that theaveraged collision speed ascertained according to equation (1) alsocorresponds to initial collision speed v_(intr,x)(0):

v _(intr,x)≈v_(intr,x)(0).   (2)

For the case that the second pressure tube sensor is situated farther tothe rear in the motor vehicle in the travel direction, and fairly hardcrash structures such as crash boxes must be deformed prior to thedeformation of the second pressure tube sensor, a decrease in thecollision speed is already present at point in time t₂. This applies inparticular for slow collisions, in which the deformation of the crashstructures results in a greater decrease in speed. In such a case, themeasured average collision speed will be slightly lower than the initialcollision speed:

v _(intr,x)<v_(intr,x)(0),   (3)

and in particular will be more apparent the slower the collision.Interestingly, v _(intr,x) measured in this way is even better suitedfor discriminating between fast and slow collisions than is theinitially “more correct” information v_(intr,x)(0).

If initial v_(intr,x) (0) is still to be ascertained in this case, thedecrease in the collision speed may be estimated via decrease in speeddv(t) of the motor vehicle during the collision. For this purpose, inanother preferred specific embodiment of the method, in particular atleast one deceleration of the motor vehicle due to a collision is takeninto account in step b) in determining a collision speed v_(intr) as theat least one collision parameter.

The decrease in speed of the motor vehicle is preferably ascertained inthe control unit (which in particular may be the central airbag controlunit) by integrating measured longitudinal acceleration signal a(t). Itis pointed out here that the collision speed during the collision may bedetermined from the relative speed of the other parties in the accidentand the rigidity ratios, whereas the decrease in speed is determinedfrom the relative speed of the other parties in the accident and themass ratios. However, since vehicle masses and rigidities show a certaincorrelation, it is a good approximation to set the decrease in thecollision speed to a decrease in speed that is rescaled with avehicle-specific factor f. Ideally, factor f also contains informationconcerning the mass and rigidity of the other party in the accident thatis obtained via C2X communication.

In general, the following may be set:

v _(intr,x)(t)=v _(intr,x)(0)−f·dv(t).   (4)

v _(intr,x)(t ₁)=v _(intr,x)(0)−f·dv(t ₁)≈v _(intr,x)(0).   (5)

v _(intr,x)(t ₂)=v _(intr,x)(0)=f·dv(t ₂).   (6)

The simplification in equation (5) reflects the fact that there is nomeasurable decrease in speed of the overall vehicle during deformationof the bumper foam. Therefore, in particular dv(t₁) may then bedisregarded.

Assuming a linear drop, for example the following applies:

v _(intr,x)=(v _(intr,x)(t ₁)+v _(intrx,x)(t ₂)/2=v _(intr,x()0)−(dv(t₁)+dv(t ₂)/2   (7)

and thus,

v _(intr,x)(0)=d/Δt+(dv(t ₁)+dv(t ₂))/2≈d/Δt+dv(t ₂)/2.   (8)

Although the dv(t) curve may be precisely determined, the assumption ofa linear decrease does not absolutely have to be made. In addition, anexact determination of v_(intr,x) (0) is possible. Integration ofv_(intr,x) (_(t)) between points in time t₁ and t₂ results in particularin distance d between the two pressure tube sensors:

$\begin{matrix}{d = {{\int_{t1}^{t2}{{v_{{intr},x}(t)}dt}} = {{{{v_{{intr}.x}(0)} \cdot \Delta}\; t} - {\int_{t1}^{t2}{d{v(t)}{dt}}}}}} & (9) \\{{{and}\mspace{14mu} {thus}},} & \; \\{{v_{{intr},x}(0)} = \frac{d + {\int_{t1}^{f2}{{{dv}(t)}{dt}}}}{\Delta t}} & \;\end{matrix}$

Thus, a particularly general rule for ascertaining the initial collisionspeed is as follows: determining points in time t₁ and t₂ and formingdifference Δt; integrating the decrease in speed between these twopoints in time, and computing according to equation (9).

However, in practice, equations (8) and also (1) allow sufficientlyaccurate determinations.

In another implementation of equation (1), it is also possible to notexplicitly compute the collision speed at all, but instead to consideronly time difference Δt, which is inversely proportional to thecollision speed.

Impact position s₁ or s₂ may be ascertained based on propagation timedifference ΔT=T_(L)−T_(R) between the pressure signals on the left andright sides of a pressure tube sensor. Since the different paths fromimpact point s (measured from the center axis, for example) to the twopressure sensors (between which the path difference is thus 2s) resultin different signal propagation times, impact position s is given bytime difference AT and speed of sound c:

s=cΔT/2.   (10)

When this method is used on both pressure tube sensors in the presentsensor configuration, two impact locations s₁ and s₂ are obtained. Thedifferences between two locations allow conclusions to be drawnconcerning the direction of the collision. For example, collision angleα may be directly ascertained via

tan(α)=(s₁−s₂)/d .   (11)

Here as well, it is possible to not explicitly compute the collisionangle according to equation (11) at all, but instead to use thedifference between impact locations s₁-s₂.

For collisions where α≠0, in fact a longer intrusion path is necessaryin order to go from a deformation of the first pressure tube sensor to adeformation of the second pressure tube sensor. This intrusion path is

I=√{square root over (d ²+(s ₁ −s ₂)²)}.   (12)

Instead of longitudinal collision speed v _(intr,x) from equation (1),the magnitude of average vectorial collision speed v _(intr) results in

$\begin{matrix}{{\overset{\_}{v}}_{{intr},x} = {\frac{I}{\Delta t} = {\frac{\sqrt{d^{2} + ( {{s1} - {s2}} )^{2}}}{\Delta t}.}}} & (13)\end{matrix}$

The direction is already specified by collision angle α determinedabove.

The ascertained features, in particular the ascertained collision speedand/or the ascertained collision angle, may be used for directly orindirectly controlling the at least one safety function (in particularrestraint means). In particular the following two specific embodimentsare preferred for this purpose.

In one preferred specific embodiment of the method, the trigger signalis output in step c) when a component v_(intr,x) of the collision speedalong the travel direction of the motor vehicle or a magnitude v _(intr)of a collision speed exceeds a first predefined threshold.

The ascertained features of the collision speed and the collisiondirection represent the key parameters for the severity of an accident,and could therefore be directly used for controlling the at least onesafety function. However, this requires a very robust integration of thepressure tubes into the motor vehicle, and full capability fordiagnosing errors in the pressure tube system (in particular includingruptures in the pressure tube).

In this specific embodiment, for trigger thresholds of a front algorithm(such as the seat belt tensioner, first stage airbag, second stageairbag, etc.), a first threshold Thd may be set to one of the collisionspeeds.

The first threshold may in particular be predefined as a fixed value.

In another preferred specific embodiment of the method, the predefinedfirst predefined threshold is predefined at least as a function of animpact location s₁, s₂ of at least one of the pressure tube sensorsand/or of a collision angle α.

The first predefined threshold may be varied in particular as a functionof collision angle α. A triggering decision may be made, for example,via averaged longitudinal collision speed v _(intr,x) according toequation (2) when

v _(intr,x)>Thd(α).   (14)

For example, for α=0° a first threshold of 20 km/h, and for α=30° afirst threshold of 26 km/h, preferably applies. In particular, athreshold value curve may be defined as a continuous function ofcollision angle α. Alternatively, the threshold values may be varied instages over certain angular ranges.

In addition, the further parameters of the collision speed describedabove may be used for the threshold value comparison. If the magnitudeof the vectorial collision speed is used for a threshold value query,analogously to equation (14), the variation as a function of collisionangle α may be less, for example.

In another preferred specific embodiment of the method, the triggersignal is output in step c) when a difference Δt between impact timest₁, t₂ of at least two of the pressure tube sensors falls below a secondpredefined threshold.

The second threshold may in particular be predefined as a fixed value.

In another preferred specific embodiment of the method, the secondpredefined threshold is predefined at least as a function of an impactlocation s₁, s₂ of at least one of the pressure tube sensors and/or of acollision angle α.

In this specific embodiment, in addition to the collision direction,impact location s₁ on the first pressure tube is also used. Thus, inparticular so-called offset collisions (in which s₁ is much differentfrom zero, but a is close to zero) may be differentiated from collisionswith full coverage (in which both s₁ and a are close to zero). Equation(14) is then generalized to

v _(intr,x)>Thd(α, s₁)   (15)

or further generalized to

v _(intr,x)>Thd(s₁, s₂),   (16)

since according to equation (11), collision angle α itself is a functionof s₁ and s₂.

It is also possible to set the threshold value queries directly tomeasured time difference Δt. An equivalent criterion for equation (16)would then be, for example,

Δt<Thd′(s₁, s₂).   (17)

In another preferred specific embodiment of the method, the triggersignal is output in step c) also as a function of at least one parameterof an additional collision recognition system.

In this specific embodiment, the triggering of the at least one safetyfunction does not take place solely via the pressure tube sensor systemin the front area of the motor vehicle. In addition, for example aconventional acceleration sensor system may be incorporated as anadditional collision recognition system. A preferred approach is for asensitivity of a conventional acceleration-based algorithm to beinfluenced in step c). This influencing is preferably a function of therecognized collision speeds, time difference Δt between impact times t₁and t₂, collision angle α, and/or impact locations s₁ and s₂. Forexample, sensitization may take place when conditions similar toequations (14) through (17) are satisfied. The sensitization itself maytake place by lowering trigger thresholds in the existing trigger logicsystems, or also by switching over to other, more sensitive triggerlogic systems. This procedure may also be referred to as a “pathconcept.”

As a further aspect, a control unit for a motor vehicle is presentedwhich is configured for carrying out the described method. Theparticular advantages and embodiment features described above for themethod are applicable and transferable to the control unit.

Furthermore, a computer program is presented which is configured forcarrying out all steps of the described method. In addition, amachine-readable memory medium is presented, on which the describedcomputer program is stored. The particular advantages and embodimentfeatures described above for the method and the control unit areapplicable and transferable to the computer program and themachine-readable memory medium.

Further particulars of the present invention as well as one exemplaryembodiment, to which the present invention is not, however, limited, aredescribed in greater detail with reference to the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an illustration of a motor vehicle including two pressuretube sensors, which is configured for carrying out the described method.

FIG. 2 shows a side cross-sectional illustration of the motor vehiclefrom FIG. 1.

FIG. 3 shows a time curve of pressures in the pressure tube sensors ofthe motor vehicle from FIGS. 1 and 2.

FIG. 4 shows an enlarged illustration of the pressure tube sensors ofthe motor vehicle from FIGS. 1 and 2.

FIG. 5 shows an illustration of the example method according to thepresent invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 shows a motor vehicle 1 that includes a first pressure tubesensor 2 and a second pressure tube sensor 3. Both pressure tube sensors2 and 3 are connected to a control unit 4. A safety function 5 may betriggered via control unit 4. For this purpose, control unit 4 is alsoconnected to an additional collision recognition system 6. The twopressure tube sensors 2 and 3 are spaced apart from one another by adistance d in travel direction x (from bottom to top in thisillustration). Vertical direction z is likewise denoted.

FIG. 2 shows one possible implementation of a 2-PTS system in motorvehicle 1 from FIG. 1. First pressure tube sensor 2 is installed in aconventional manner in a bumper 9, in a groove of absorption foam 7 thatrests on a crossbeam 14. In the present example, second pressure tubesensor 3 is mounted on a radiator crossbeam 15. A mechanical element,not foam, is provided as an absorption element 8 (energy absorber). Thespecific design is not critical. The task of absorption element 8 issolely to couple the force to second pressure tube sensor 3 in acontrolled manner and to mechanically protect same. The example in FIG.2 shows in particular that pressure tube sensors 2 and 3 do notnecessarily have to be situated at the same height (in the directionfrom top to bottom in the illustration).

FIG. 3 shows a time curve of pressures p in pressure tube sensors 2 and3 of motor vehicle 1 from FIGS. 1 and 2. A first pressure signal 10 isrecorded with a left pressure sensor of first pressure tube sensor 2,and a second pressure signal 11 is recorded with a right pressure sensorof first pressure tube sensor 2. A third pressure signal 12 is recordedwith a left pressure sensor of second pressure tube sensor 3, and afourth pressure signal 13 is recorded with a right pressure sensor ofsecond pressure tube sensor 3. It is particularly apparent that thepressure rise in second pressure tube sensor 3 occurs later than infirst pressure tube sensor 2. Impact times t₁ and t₂ differ by a timedifference Δt, corresponding to distance d between pressure tube sensors2 and 3. It is further apparent that the pressure rise in the respectiveleft pressure sensors occurs earlier. This is due to the fact that theimpact location in the present example is situated left of center ofmotor vehicle 1, and the pressure waves accordingly reach the leftpressure sensors earlier. This example thus involves a collision on theleft side.

FIG. 4 shows an enlarged illustration of pressure tube sensors 2 and 3of motor vehicle 1 from FIGS. 1 and 2. Travel direction x pointsupwardly in this case. Longitudinal distance d (i.e., measured indirection x) between the two pressure tube sensors 2 and 3 isparticularly apparent. The impact of a collision partner is indicated byan arrow 16. The impact takes place at a collision angle α. Impactlocations s₁ and s₂ indicate where the collision partner strikespressure tube sensors 2 and 3, as measured from the center (indicated bya dashed line) of pressure tube sensors 2 and 3.

FIG. 5 is a schematic illustration of a method for generating a triggersignal for triggering at least one safety function 5 of a motor vehicle1, including the method steps:

a) receiving respective signals from at least two pressure tube sensors2 and 3,

b) determining at least one collision parameter from the signalsreceived according to step a),

c) outputting the trigger signal for the at least one safety function 5as a function of the at least one collision parameter determined in stepb).

1-13. (canceled)
 14. A method for generating a trigger signal fortriggering at least one safety function of a motor vehicle, the methodcomprising the following steps: a) receiving respective signals from atleast two pressure tube sensors; b) determining at least one collisionparameter from the received respective signals received according tostep a); c) outputting the trigger signal for the at least one safetyfunction as a function of the determined at least one collisionparameter determined in step b).
 15. The method as recited in claim 14,wherein the ate least two pressure tube sensors from which therespective signals are received in step a) are spaced apart from oneanother at least in a travel direction of the motor vehicle.
 16. Themethod as recited in claim 14, wherein each of the respective signal ofthe at least two pressure tube sensors received in step a) represent atleast one of the following parameters: (i) an impact time; and (ii) animpact location.
 17. The method as recited in claim 14, wherein the atleast one collision parameter determined in step b) is at least one ofthe following: (i) a magnitude of a collision speed; (ii) a component ofthe collision speed along a travel direction of the motor vehicle; (iii)a collision angle.
 18. The method as recited in claim 14, wherein atleast one deceleration of the motor vehicle due to a collision is takeninto account in step b) in determining a collision speed as the at leastone collision parameter.
 19. The method as recited in claim 14, whereinthe trigger signal is output in step c) when a component of a collisionspeed along a travel direction of the motor vehicle or a magnitude ofthe collision speed exceeds a first predefined threshold.
 20. The methodas recited in claim 19, wherein the first predefined threshold ispredefined at least as a function of an impact location of at least oneof the pressure tube sensors and/or of a collision angle.
 21. The methodas recited in claim 14, wherein the trigger signal is output in step c)when a difference between impact times of at least two of the pressuretube sensors falls below a second predefined threshold.
 22. The methodas recited in claim 21, wherein the second predefined threshold ispredefined at least as a function of an impact location of at least oneof the pressure tube sensors and/or of a collision angle.
 23. The methodas recited in claim 14, wherein the trigger signal is output in step c)as a function of at least one parameter of an additional collisionrecognition system.
 24. A control unit for a motor vehicle that isconfigured to generate a trigger signal for triggering at least onesafety function of a motor vehicle, the control unit configured to: a)receive respective signals from at least two pressure tube sensors; b)determine at least one collision parameter from the received respectivesignals received according to a); c) output the trigger signal for theat least one safety function as a function of the determined at leastone collision parameter determined in b).
 25. A non-transitorymachine-readable memory medium on which is stored a computer program forgenerating a trigger signal for triggering at least one safety functionof a motor vehicle, the computer program, when executed by a computer,causing the computer to perform the following steps: a) receivingrespective signals from at least two pressure tube sensors; b)determining at least one collision parameter from the receivedrespective signals received according to step a); c) outputting thetrigger signal for the at least one safety function as a function of thedetermined at least one collision parameter determined in step b).